In recent years many advances have been made by which handicapped persons, particularly those confined to wheelchairs, have enjoyed greater freedom of movement and mobility.
In the past, it has always been difficult to transport handicapped persons confined to wheelchairs from place-to-place within the community using conventional vehicles. On occasion, various civic and charitable groups have purchased and equipped special van-type vehicles to carry wheelchairs. The equipment installed in such vehicles includes various ramps and lift mechanisms by which occupied wheelchairs can be transferred to and from the ground level to the floor level of the van.
Many of the various types of wheelchair lifts which have been developed and are installed in such van-type vehicles are relatively cumbersome and complex in construction and their installation and maintenance are usually costly and time consuming. Many of the wheelchair lifts currently available are not entirely reliable and in cases of a power or hydraulic failure when the lift is in actual operation passenger safety has been a matter of serious concern. The paramount criterion of any wheelchair lift is safety and that in any emergency or power failure, the handicapped person will be safely lowered to the ground. Another requirement is that the construction of the lift facilitates its installation and that the components are simple in construction and reliable in operation whereby lift maintenance is economical.
The principal object of this invention is to provide a wheelchair lift for installation in van-type vehicles which is simple in construction, highly reliable in operation and which can be readily installed in various conventional vans without vehicle modification.
Another object of this invention is to provide a wheelchair lift of the above type which is capable of safely lowering an occupied wheelchair from a vehicle floor level to the ground, even in the case of a power or hydraulic failure.
A further object of this invention is to provide a wheelchair lift of the above type in which a single hydraulic cylinder serves to lower, raise and completely fold the lift within the doorway opening of a van-type vehicle and in which the lowering of a wheelchair on the lift can be safely carried out even in the case of a power or hydraulic failure, such as the rupture of a fluid line.
Yet another object of this invention is the provision of mechanism means to initiate the unfolding and pivoting of the lift platform without power assistance. In this connection, potential energy is stored during the folding of the lift platform wherein some of the kinetic energy required for raising and folding the lift is subsequently utilized for this purpose.
Still a further object of this invention is the provision of mechanical means for raising, lowering, folding and also operating a safety ramp on the platform which includes a continuous length of cable on each side of the lift wherein a safety ramp is automatically pivoted by the cables to its closed position before the platform can be raised and then folded by the same cables.